JPH0639442Y2 - Flyback transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a flyback transformer used for applying a high DC voltage to a cathode ray tube of, for example, a devision receiver, a display device, etc. The present invention relates to an improvement of a winding type flyback transformer.

[Conventional technology]

Generally, the flyback transformer is mainly composed of a section winding type and a coaxial multi-layer winding type due to the winding method of the high voltage coil.
The former section winding type is constructed by dividing a high-voltage coil into a plurality of high-voltage winding blocks in the axial direction of a high-voltage bobbin and winding the same. The high-voltage bobbin is divided into a plurality of high-voltage winding layers and wound coaxially in the radial direction of the high-voltage bobbin.
The coaxial multilayer winding type flyback transformer has recently been put into practical use because it can reduce the output impedance as a single unit and improve the high voltage regulation.

Therefore, a coaxial multilayer winding type flyback transformer according to the first conventional technique will be described with reference to FIGS.

First, FIG. 5 shows the overall structure. In FIG.
Is a core formed by abutting "U" -shaped core members 1a, 1a, 2 is a low pressure bobbin inserted through one leg 1b of the core 1, and the low pressure bobbin 2 A low-voltage coil 3 having a predetermined number of turns is wound around the outer periphery by section winding. Reference numeral 4 is a high-pressure bobbin which is provided so as to be fitted onto the low-pressure bobbin 2. On the outer periphery of the high-voltage bobbin 4, five winding layers 6 to 10 are formed as a high-voltage coil 5 in a coaxial multi-layer form via an interlayer paper 11. It is wound around. Reference numeral 12 denotes five high voltage diodes 12a to 12e, which are high voltage diodes 12a to 1e.
2e are alternately connected in series with the winding layers 6 to 10 of the high voltage coil 5.

Further, FIG. 6 shows a circuit configuration. The high voltage side end of the low voltage coil 3 is connected to a horizontal output circuit (not shown) so that a collector pulse is applied. On the other hand, in the high voltage coil 5, the winding start end 6a of the first winding layer 6 on the lowest pressure side is directly grounded to the ground 13, and the winding layer 10 on the highest pressure side is the high voltage diode for output. 12e is connected to the anode of the cathode ray tube through a high voltage cable 14 (anode lead).

In the flyback transformer configured in this way,
When a collector pulse is applied to the low voltage coil 3 from the horizontal output circuit, each winding layer 6 to 10 of the high voltage coil 5 is determined by the number of turns of each winding layer 6 to 10 as shown in FIG. A flyback pulse similar to the collector pulse is induced. Here, in FIG. 7, assuming that the DC zero potential is DC = 0 and the AC zero potential is AC = 0, the induced flyback pulse has the AC zero potential (AC = 0) as the neutral point. With a positive voltage E ₁ . In the flyback pulse thus induced, the high voltage diode 12 is generated when the AC = 0 level or higher in the first winding layer 6.
rectification is performed by a, and for the second and subsequent winding layers 7-10, high-voltage diodes 12b-12e additionally rectify AC = 0 level or higher, and as a whole rectify the hatched portion in FIG. The high voltage diode 12e outputs a direct current high voltage having a voltage E and a current I to the cathode ray tube.

[Problems to be solved by the device]

By the way, for the purpose of reducing the voltage fluctuation due to the load fluctuation of the high voltage DC voltage output from the flyback transformer, the capacitance between the grounding layers of the winding layers constituting the high voltage coil is equivalently reduced to It is necessary to increase the order of harmonics induced on the side, in other words, to enable higher-order resonance.

Therefore, as a method of equivalently reducing the capacitance between each winding layer and the ground, it is conceivable to reduce the voltage induced between both ends of each winding layer. That is, in general, the capacitance of the capacitor is proportional to the voltage, and thus lowering the voltage across each winding layer results in lowering the capacitance between each winding and the ground.

However, according to the above-described first conventional technique, the flyback pulse induced in each winding layer 6 to 10 has a high positive voltage E ₁ above the AC = 0 level, which is the neutral point, and the capacitance between the ground and ground. There is a drawback that it becomes large and good high-order resonance cannot be performed.

For this reason, by reducing the positive voltage level between both ends of each winding layer, the capacitance between each winding layer 6 to 10 is reduced, and higher-order resonance is enabled. A second conventional technique shown in FIG. 9 is known.

8 and 9, the same components as those in the first prior art are designated by the same reference numerals, and the characteristic of the second prior art is that the winding of the first layer on the lowest pressure side is the same. The winding start end 6a of the layer 6 is connected to the cathode side of the diode 15, and the anode side of the diode 15 is connected to the ground 13.

In the second conventional technique, as shown in FIG.
An AC positive pulse component B having a voltage E ₂₁ that is measured from the winding start end 6a to the winding end end 6b of the first winding layer 6 with reference to the AC zero potential (AC = 0), Start of winding from ground 13
A flyback pulse composed of an AC negative pulse component C having a voltage E ₂₂ of 6a is induced, and a similar flyback pulse is also induced in the second and subsequent winding layers 7 to 10. . Here, the ratio of the voltage E ₂₁ and the voltage E ₂₂ is 7: 3 to 8: 2.
Is the ratio.

By providing the diode 15 at the winding start end 6a of the first winding layer 6 as described above, the alternating current induced in the winding layers 6 to 10 as shown by the diagonal lines in FIG. All the DC-positive pulse components B including the negative pulse component C are added and rectified. By the way, when compared with the above-mentioned first prior art, E ₂₁ + E ₂₂ = E ₁ (1), and the DC voltage E output from the output high voltage diode 12e to the cathode ray tube is the above-mentioned 1 is equivalent to that of the prior art.

Thus, in the second prior art, the ratio of the positive pulse component B and the negative pulse component C is 7: 3 to 8: 2, which is compared with the above-mentioned first prior art. As a result, the proportion of the positive pulse component B decreases and the positive voltage across the windings 6 to 10 decreases, so that the capacitance between each winding layer 6 to 10 and the ground decreases, and as a result, the higher resonance occurs. It becomes possible to reduce the load fluctuation as compared with the first prior art.

However, in the second prior art, the ratio of the positive pulse component B and the negative pulse component C is 7: 3 to 8: 2,
The proportion of the positive pulse component B is still large. Therefore, there is a drawback that the load fluctuation cannot be sufficiently reduced.

Furthermore, as a modification of the above-mentioned second conventional technique,
The third conventional technique shown in FIGS. 1 to 12 is also known.

In the figure, the same components as those of the first conventional technique are designated by the same reference numerals, and the characteristic features of the third conventional technique are as follows.
As shown in FIG. 10, the winding width L ₁ of the _first winding layer 16 is approximately half the winding width L ₂ of the second and subsequent winding layers 7 to 10, and the winding end L
By setting 16b at the same position as the winding end ends 7b to 10b of the second and subsequent winding layers 7 to 10, the winding start end of the first winding layer 16 is formed.
The missing part 17 of the winding layer is provided on the 16a side (10th,
(See Figure 11).

In the flyback transformer of the third prior art configured as described above, the missing portion 17 of the first winding layer 16 causes the collector to be provided in the first winding layer 16 as shown in FIG. An AC-positive pulse component D having a voltage E ₃₁ similar to a pulse is induced, and in the winding layers 7 to 10 on the second and subsequent layers,
An AC positive pulse component D having the same waveform as the flyback pulse D induced in the first winding layer 16 and having the same voltage E ₃₁ , and the positive pulse component D and AC And a negative pulse component E having a negative voltage E ₃₂ which is symmetrical with respect to the zero potential point (AC = 0) of AC and is AC-induced. Here, E ₃₁ = E ₃₂ (2) holds between the voltages E ₃₁ and E ₃₂ .

Then, as indicated by hatching in FIG. 12, the flyback pulse induced in the first winding layer 16 is rectified by the high voltage diode 12a in the AC positive portion D, and the second and subsequent winding layers are rectified. In 7 to 10, the high voltage diodes 12b to 12e add and rectify the positive pulse component D and the negative pulse component E. Here, when the third prior art is compared with the above-mentioned first and second prior arts, E ₁ = E ₂₁ + E ₂₂ = E ₃₁ + E ₃₂ (3) Therefore, from the output diode 12e, It can be said that the DC voltage output to the cathode ray tube is substantially the same as that of the above-mentioned first and second conventional techniques.

However, since the negative pulse component E induced in the second and subsequent winding layers 7 to 10 is larger than that in the second prior art and the positive pulse component D is decreased, these winding layers 7 to 10 are reduced. The apparent positive voltage level of .about.10 decreases, and the capacitance between the ground and ground decreases, and as a result, the load fluctuation can be further suppressed as compared with the first and second conventional techniques.

However, in the third conventional technique, the number of turns of the first winding layer 16 is half that of the above-described first and second conventional techniques, and therefore the induced voltage per turn is too large,
There is a problem that dielectric breakdown easily occurs. That is,
For example, if a high voltage of 30 KV is induced in 3000 turns, 10 V is induced per turn, whereas if 30 KV is induced in 1500 turns, 20 V is induced per turn. As a result, the flyback transformer as a whole has a structure in which insulation breakdown is apt to occur, resulting in inferior safety.

The present invention has been made in view of the above-mentioned drawbacks of the related arts. The magnitude of the negative pulse component induced in each winding layer of the high voltage coil is relatively increased to increase the magnitude of the positive pulse component. By suppressing the output voltage, it is possible to reduce the load fluctuation by reducing the capacitance between each winding layer and the ground while keeping the output high voltage applied to the cathode ray tube constant, and also to reduce the withstand voltage on the high voltage coil side. The purpose is to provide a flyback transformer.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the flyback transformer adopted by the present invention is characterized in that a diode is provided between the winding start end of the first winding layer of the high voltage coil and the ground, and the cathode of the diode is provided. The side is connected to the winding start end, the anode side is connected to ground, and the intermediate point of the first winding layer is connected to ground via a capacitor.

[Action]

With this configuration, when a collector pulse is applied to the low voltage coil, the first winding layer of the high voltage coil has a positive pulse component and a negative pulse component that is substantially equal to the positive pulse component. A flyback pulse is triggered. On the other hand, a flyback pulse composed of a positive pulse component and a negative pulse component having substantially the same magnitude as the positive pulse component is induced in the second and subsequent winding layers. Is subjected to additive rectification, and the positive and negative pulse components of the first winding layer are subjected to additive rectification and output as a high-voltage DC voltage. Thus, by increasing the negative pulse component and decreasing the relatively positive pulse component,
Since the output high voltage is kept constant and the capacitance between the winding layers and the ground is reduced, the low-voltage coil and the high-voltage coil resonate in a higher order, and the load fluctuation is reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

The low-voltage coil 3 wound around the low-voltage bobbin, and the high-voltage coil 5 wound around the high-voltage bobbin located on the outer peripheral side of the low-voltage coil 3 by being divided into a plurality of coaxial winding layers 6-10. ,
The point of having a plurality of high voltage diodes 12a to 12e which are alternately connected in series with the winding layers 6 to 10 of the respective layers of the high voltage coil 5 is that of the first prior art shown in FIGS. Since they are similar to those described above, the same reference numerals are given to them, and the description thereof will be omitted.

1 and 2 show a first embodiment of the present invention.

Reference numeral 21 denotes a diode provided between the winding start end 6a of the first winding layer 6 of the high-voltage coil 5 and the ground 13.
The anode side of 21 is connected to earth 13 and the cathode side is 1
It is connected to the winding start end 6a of the winding layer 6 of the first layer.

Reference numeral 22 denotes a capacitor, which is connected between the intermediate point 6c in the lengthwise direction of the first winding layer 6 and the ground 13 and connects the intermediate point 6c to an AC zero potential (AC = 0). ) Is set.

The flyback transformer of this embodiment is configured in this way, and its operation will be described next.

When a collector pulse is applied to the low voltage coil 3, a flyback pulse is induced in each winding layer 6 to 10 of the high voltage coil 5. However, since the diode 21 is provided on the winding start end 6a side of the first winding layer 6 here, a negative pulse is applied to the winding start end 6a side of the first winding layer 6 concerned. The component F is induced, and the positive pulse component G is induced on the winding end 6b side.
The midpoint 6c of the first winding layer 6 is an AC zero potential (AC =
0), the positive pulse component F and the negative pulse component G are symmetrical with respect to the AC zero potential (AC = 0) and both have the same magnitude. That is, the AC zero potential (AC
= 0) as a reference, the winding start end 6a of the first winding layer 6
The negative pulse component F of the voltage E ₄₁ is induced in the
A positive pulse component G of the voltage E ₄₂ is induced in b, and E ₄₁ = E ₄₂ (4).

On the other hand, since the first winding layer 6 and the second and subsequent winding layers 7 to 10 are strongly coupled capacitively, the first and second winding layers 7 to 10 are also the first layers. A flyback pulse having the same waveform as that of the winding layer 6 is induced.

Here, when this embodiment is compared with the first, second, and third conventional techniques, the following expression (5) is established.

E ₄₁ + E ₄₂ = E ₃₁ + E ₃₂ = E ₂₁ + E ₂₂ = E ₁ (5) Therefore, also in the present embodiment, the size is substantially equal to that of the flyback transformers of the first, second and third conventional techniques. It is possible to output the DC high voltage of the above to the cathode ray tube.

However, when the present embodiment is compared with the first and second conventional techniques, the magnitude of the positive pulse component G induced in the high voltage coil 5 can be suppressed to be lower than that of the conventional one. Positive voltages above the neutral point induced in each winding 6-10 can be reduced. Therefore, it is possible to reduce the capacitance of each winding layer between 6 and 10 with respect to the ground, which enables high-order resonance between the low voltage coil 3 and the high voltage coil 5,
Load fluctuations can be reduced.

Further, in the third conventional technique, the number of turns of the first winding layer 16 is half the number of turns of the second and subsequent winding layers 7 to 10, whereas in the third embodiment, Since the winding layer 6 of the first layer has the same number of turns as the winding layers 7 to 10 of the second and subsequent layers, the induced voltage per turn is lower than that of the third prior art,
Withstand voltage can be lowered and stability can be improved.

Next, FIG. 3 shows a second embodiment of the present invention.

The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Reference numeral 31 is a resistor, and the resistor 31 is connected between the capacitor 22 and the ground 13.

Thus, in the case of such a configuration, the AC component of the flyback pulse induced on the high voltage coil 5 side is supplied to the resistor 31 via the capacitor 22 and disappears at the resistor 31, so the high voltage coil 5 The high DC voltage output from the cathode ray tube to the cathode ray tube can be ringingless.

Further, FIG. 4 shows a third embodiment of the present invention.

The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Reference numeral 41 is a ringing elimination circuit.
Is configured by connecting a resistor 42 and a coil 43 in parallel, and the ringing removal circuit 41 is connected between the capacitor 22 and the ground 13. Even with this structure, ringing can be removed as in the second embodiment.

[Effect of device]

As described above, according to the present invention, a diode is connected between the winding start end of the first winding layer of the high voltage coil and the ground, and the intermediate point in the length direction of the first winding layer. Is connected to the ground via a capacitor to reduce the positive pulse component induced in each winding layer of the high voltage coil to reduce the capacitance between the ground and the low voltage coil and the high voltage coil. Higher-order resonance between the two is possible, and the load fluctuation can be suppressed well. Further, since the number of turns of the first winding layer of the high-voltage coil is made equal to the number of turns of the second and subsequent winding layers by effectively using the bobbin, the induced voltage per turn can be small, The breakdown voltage can be lowered.

[Brief description of drawings]

1 and 2 relate to a first embodiment of the present invention, FIG. 1 is a circuit configuration diagram of a flyback transformer, and FIG. 2 is a waveform diagram of flyback pulses induced in each winding layer of a high voltage coil, FIG. 3 is a circuit configuration diagram of a flyback transformer showing a second embodiment of the present invention, FIG. 4 is a circuit configuration diagram of a flyback transformer showing a third embodiment of the present invention, and FIGS.
FIG. 5 relates to the first prior art, FIG. 5 is a longitudinal sectional view of a flyback transformer, FIG. 6 is a circuit configuration diagram thereof, and FIG. 7 is a waveform diagram of a flyback pulse induced on the high-voltage coil side,
8 and 9 relate to the second prior art, FIG. 8 is a circuit configuration diagram of a flyback transformer, FIG. 9 is a waveform diagram of a flyback pulse induced on the high-voltage coil side, and FIGS. FIG. 12 relates to the third prior art, FIG. 10 is a longitudinal sectional view of a flyback transformer, FIG. 11 is its circuit configuration diagram, and FIG. 12 is a waveform diagram of voltage induced on the high-voltage coil side. . 2 ... Low-voltage bobbin, 3 ... Low-voltage coil, 4 ... High-voltage bobbin, 5 ... High-voltage coil, 6,7,8,9,10 ... Winding layer, 12a-1
2e …… High voltage diode, 13 …… Ground, 21 …… Diode, 22 …… Capacitor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-9367 (JP, A) JP-A-60-100881 (JP, A) Actual opening 52-88933 (JP, U) Actual opening 62- 111791 (JP, U) Actual development Sho 57-62777 (JP, U) Japanese public Sho 59-18846 (JP, B2)

Claims (1)

[Scope of utility model registration request] 1. A low-voltage coil wound on a low-voltage bobbin, a high-voltage coil wound around a high-voltage bobbin located on the outer peripheral side of the low-voltage coil in a coaxial multi-layered manner and divided into a plurality of winding layers, and the high-voltage coil. In a flyback transformer consisting of a winding layer of each layer of the coil and a plurality of high-voltage diodes alternately connected in series, a diode is provided between the winding start end of the first winding layer of the high-voltage coil and ground. The cathode side of the diode is connected to the winding start end, the anode side is connected to ground, and the midpoint in the length direction of the first winding layer is connected to ground via a capacitor. Flyback transformer.